I recently came across an issue with thread breaking/knotting with my Pfaff 145 H3. Im using tex 60 thread in both the upper threading as well as the bobbin, with a 110/18 needle to accompany (ive tried 100/16 as well).
Here is an imgur link to a video of me handcranking the machine - I unfortunately couldnt upload the video as an attachment here as I exceeded the file size limit - https://imgur.com/a/mByhkyW
As shown in the video, the thread jams afters a couple of cranks (timestamp is 0:10 seconds left in the video). In trying to automatically sew (i.e, turn the machine on and sew), I get the same issue - thread breaking and knotting after 2-3 stitches.
The issue originally started after I noticed some of the bobbin thread was showing in my top stitches. No biggy, right? Well, to remedy this, I followed the manual provided by Pfaff and tried loosening the upper tension as well as tightening the bobbin tension to no avail. After messing around on both ends for a bit, the thread began to jam as you can see in the video. I've continued to adjust both tensions to see if I could get back to square one (loosening/tightening both threads) to no avail as well. Ive also tried cleaning out the bobbin, re-threading both the bobbin and upper thread, and re-screwing the upper tension.
Any ideas as to what can be causing this?